Check your cable connections.

Check your cable connections with a infrared heat gun, even if they look tight and good. Check them at a high current draw. I make my own, I have a hydraulic crimper and the correct cable lugs. I was putzing around checking things and noticed one of my 4/0 cables was hot, one end too hot to touch. Lithium batteries will accept a lot of current, I was pushing somewhere around 110A @ 12Vdc. I made a new cable and, under the same conditions, all cables and connections in the entire system are basically room temp.
I don't want to get into a discussion of what is the best method of crimping or whether to crimp or solder. I have been doing this for a long time. I just think, even if you buy your cables already terminated, a heads up is in order.

Dick

somewhereinusa said:

Check your cable connections with a infrared heat gun...

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You mean with something like this?

svetz said:

You mean with something like this?
View attachment 1093

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Yes, the one I have has an aiming device, two laser dots, for making sure you are the right distance. When the dots merge into one you are at the optimal distance for the reading.

NUB8580

Even the ones with just a laser pointer are probably good enough.

I also use it to check things like my digital thermostats to adjust for as much accuracy as I can get.

Dick

This is an excellent advise based on years of experience. Also, make sure lug is bolted tight, but don't exceed torque value, stripping the threads in your expensive battery ( depends on terminal type ). Use lock washers, but never ever put any washers under the lug. Yes, I have seen people do that. The steel washer turns red hot and melts the terminal. Use bolts with enough thread to make good torque, but not too long to bottom out and leave the loose lug. So many ruined batteries because of these simple mistakes.
If your lug/terminal/cable are too hot to hold the hand on it when under max continuous current, then you did something wrong, up to and including using wrong cables/lugs/battery size, etc. Properly designed system should not get too hot to touch at any point.